Re: pcap_inject() fails with rc 0 on HP-UX

["Harley Stenzel" <hstenzel () gmail com>]

On 4/3/06, Rick Jones <rick.jones2 () hp com> wrote:
> > 4) What is the expected interaction of multiple libpcap instances on
> > HP-UX?  I can't use my program and tcpdump at the same time; something
> > I can do on other OSes.
>
> I believe this is a long-standing limitation of promiscuous mode support
> in HP-UX - only one process may have a promiscuous stream open on an
> interface at one time.  I believe that is the case for DL_PROMISC_PHYS
> (give me everything that reaches the NIC). I cannot recall if that would
> be the same for the lesser "give me everything that the NIC gives the
> host" DL_PROMISC_SAP.

Using tcpdump as an example:

bash-3.00# tcpdump -p -i lan2 > /dev/null &
[1] 14650
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on lan2, link-type EN10MB (Ethernet), capture size 96 bytes

bash-3.00#  tcpdump -p -i lan2 > /dev/null
tcpdump: recv_ack: promisc_sap: UNIX error - Device busy

So, even without promiscous mode, it is not possible on HP-UX to have
multiple libpcap instances on the same nic.

> If you need/want that limitation lifted, definitely get in touch with
> the HP Response Centre and excercise your support contract(s) to have an
> enhancement request opened against DLPI.

Thanks, we may do that.  It is inconvenient to not be able to use
tcpdump and a lipbcap app simultaneously.

> Does your program actually require promiscuous mode to function?

No, it does not require promiscous mode.  It does need to register
multiple ethernet multicast addresses,  however.

> rick jones

--Harley
-
This is the tcpdump-workers list.
Visit https://lists.sandelman.ca/ to unsubscribe.